diff --git a/plat.mk b/plat.mk
index 7431ccbaf27751a84957324174e6710f44c3af84..26efe4dd27e9254f2b6742c4cda01740cb59d643 100644
--- a/plat.mk
+++ b/plat.mk
@@ -18,8 +18,7 @@
 ifeq ($(strip $(PLAT)), Unisoc)
 CFLAGS_PLAT = 	-mcpu=cortex-a5 -mtune=generic-armv7-a -mthumb \
 				-mfpu=neon-vfpv4 -mfloat-abi=hard -mno-unaligned-access
-				
-DFLAGS_PLAT = _SYS_SELECT_H _TIMEVAL_DEFINED
+
 
 ifeq ($(USE_NANO_LIB), y) # use nano lib
 STD_LIBS += $(COMPILER_PATH)/$(CROSS)/lib/thumb/v7-a+fp/hard/libc_nano.a
@@ -85,8 +84,6 @@ CFLAGS_PLAT = 	-march=xcpu2 -mtune=xcpu2 -mips16 -msoft-float \
 				-fweb \
 				-G0
 
-DFLAGS_PLAT = _SYS_SELECT_H _TIMEVAL_DEFINED
-
 LDFLAGS_PLAT = $(EL_FLAG)
 
 STD_LIBS += $(COMPILER_PATH)/lib/gcc/$(CROSS)/7.1.0/xcpu2/mips16/libgcc.a \
diff --git a/system/lwip/Unisoc/include/lwipopts.h b/system/lwip/Unisoc/include/lwipopts.h
index 1c89e6495d1fdb2e04b793b6911b1d0b45000448..73d8b14935c73ed29987165baed7bf51e53ddc07 100644
--- a/system/lwip/Unisoc/include/lwipopts.h
+++ b/system/lwip/Unisoc/include/lwipopts.h
@@ -187,7 +187,7 @@
 #define LWIP_ARP 1
 #define LWIP_TIMERS 0
 ////Modified by Freddy @20210816 This must be set to 1 in pythonSDK, otherwise compilation will fail
-#define LWIP_TIMEVAL_PRIVATE 1
+#define LWIP_TIMEVAL_PRIVATE 0
 
 /* Enable DHCP to test it, disable UDP checksum to easier inject packets */
 #define LWIP_DHCP 1